3232 THE AMERICAN NATURALIST. [Vou. XXXVII 
(hypogenic), development from the egg ; while in others, and by 
far the larger number, development is indirect (metagenic), 
exhibiting perfectly evident alternation of generations ; in this 
case however, involving a distinct metamorphosis, the polyp 
giving rise to a free-swimming ephyra which is in tum trans- 
formed directly into a medusa. It should also be noted that 
asexual budding is, unlike that of the former class, by the 
transverse fission of the polyp body into a series of disks which 
become free as ephyre, as already noted. Direct asexual 
budding from medusoid organs, common in many Hydromeduse, 
is unknown among the Scyphomeduse. 
SYNOPSIS OF THE ORDERS. 
I. STAUROMEDUS&.  Scyphomeduse with vasiform or  sub-conical 
umbrella. In some cases sedentary, attached by an aboral peduncle or 
stalk. Wholly devoid of sensory organs, but with eight tentacles. or 
tentacular organs which serve as anchors. Stomach with four wide 
gastric pouches which communicate with a marginal canal. Gonads in 
four crescentic loops on the floor of the gastric pouches. 
Il. PEROMEDUS&. Scyphomeduse with bell more or less conical in shape 
and with a usually well-developed horizontal constriction which divides it 
into two regions ; an aboral, resembling quite remarkably the apical projec- 
tion of the bell of certain Hydromeduse; the marginal portion, which 
is eight or sixteen lobed and bearing tentacles and rhopalia or tentacu- 
locysts. Stomach capacious with four gastric pouches which are separated 
by narrow septa, and extending into a circular sinus. Gonads much as 
in the former order. 
II]. Cusomepus&. Scyphomeduse with a distinctively quadrate 
umbrella, provided with a well-defined velarium, which is supported at the 
radial angles by thickenings or frenula. Marginal tentacles four, 
interradially disposed, and with four perradial rhopalia. Bases of 
tentacles often provided with wing-like expansions, pedalia. 
IV. DiscomMEDuS&. Scyphomedusz with shallow, or disk-shaped, eight 
lobed umbrella. Marginal sense organs eight, per- and interradially dis- 
posed about the margin. Tentacles often very numerous. Manubrium 
often very large, pendulous and complexly frilled or plaited. Stomach 
with four to eight or more gastric pouches, within which are borne 
the gonads. 
The meduse of this order are often of large size. Specimens of Cyanea 
reaching a diameter of from four to six feet in some cases and with ten- 
tacles having an extent of more than fifty feet when fully extended. The 
average size however, even of this species, is very much smaller, as will 
be noted later. 
